A developing unit for developing an electrostatic latent image formed on a photoreceptor belt is provided in a liquid electrophotographic printer. The developing unit, as shown in FIG. 1, includes a developing roller 13 for developing an electrostatic latent image by supplying a developer 1, which is a mixture of powdered toner and a liquid carrier, to the photoreceptor belt, and a squeeze roller 11 for removing excess developer from the photoreceptor belt 10.
The squeeze roller 11 presses the photoreceptor belt 10 against a backup roller 12 during printing to remove the excess developer. After printing, the squeeze roller 11 is separated from the photoreceptor belt 10 and the pressing force is removed.
To perform the above operation, a squeeze roller elevating apparatus is provided in a liquid electrophotographic printer so that the squeeze roller 11 is separated from the photoreceptor belt 10 when no printing is performed, and is elevated and pressed against the photoreceptor belt 10 during printing.
The structure of a conventional squeeze roller elevating apparatus is shown in FIG. 2. A squeeze frame 20 having a squeeze roller 11 is installed at a main frame 40 to be capable of elevating. The squeeze frame 20 is elevated by a cam 22 rotated by a driving motor (not shown) and thus, the squeeze roller 11 can be elevated. Reference numeral 30 refers to a belt frame which supports the photoreceptor belt 10 so as to not deviate from a regular circulation path.
In the squeeze roller elevating apparatus, since the squeeze frame 20 must be elevated to elevate the squeeze roller 11, an extra space is required for the elevation thereof. Also, a large driving force is needed to elevate the squeeze frame 20.